Snap switches are usually provided with a moving, preferably pivoting, contact lever and a switching member which acts upon it by means of spring action. In this case, the switching member is usually moved by means of a plunger sliding in a straight direction.
In order to achieve a sudden switching action, the spring engages first above and then below the longitudinal axis of the pivoting contact lever, depending on the movement of the switching member. Thus, a sudden reversal of the torque acting on the contact lever is attained. A snap switch of this kind is described, for example, in DE-PS 29 28 214. A disadvantage of the snap switch described therein is that the contact force of the contact lever is reduced to zero shortly before the switching process, so that the switching contact is not securely in place just before the switching. That can lead to an increase in the switch resistance shortly before the switching and also increased wear due to arcing and the like.
Additional consideration has been given to increasing the contact force of the contact lever shortly before the switching process instead of trying to reduce it. Due to that, an increasing contact force of the contact on the contact lever is obtained with respect to the fixed contact. This lasts up to the time when the contact lever is switched under a sudden change of direction of the comparatively large contact force, and then sets with large force onto the opposing contact. The contact force decreases somewhat after the end of the plunger movement. A similar switch is described, for example, in DE-PS 39 40 285. This already known switch pertains to a make contact. However, it can also be designed as a break contact or as a changeover switch while retaining the stated advantages.
On the other hand, a disadvantage of the switch according to DE-PS 39 40 285 is that a switching member (16) and a contact lever (33) are located essentially in the same plane. For that reason, a housing must be chosen long enough that it can hold the two components arranged in succession. In addition, the straight movement of a plunger (46) in this switch must be converted into a pivot motion of the switching member (16).
Therefore, a change was made, and DE-PS 39 42 925 discloses the switching member in the housing on a straight path extending essentially perpendicularly to the longitudinal direction of the contact lever. A disadvantage of this known switch, however, is that its housing is integrated as a single piece into a support element, i.e., the housing of the switch and also the support element itself are cast as a single piece of plastic. When using several switches, the switch housing can be assembled only with the components of the switch in the direction of the support element, that is, perpendicular to the plane of the support element. But assembling parallel to the plane of movement of the contact lever is comparatively difficult and can only be practically implemented by manual means. This is because individual components of the switch must necessarily undercut each other in the plane of movement of the contact lever, so that in the direction of installation they can only be inserted into the switch one after the other. In addition, the installation surface bounded by the side walls of the switch is comparatively small, so that only a comparatively small installation window is available for assembling.